Imagine a personal heating system that works indoors as well as outdoors, can be taken anywhere, requires little energy, and is independent of any infrastructure. It exists – and is hundreds of years old.
I got one of these several years ago because I just missed the simplicity of having one to warm up with. We did have one in the house when I was a kid that my grandparents left, so the idea didn’t come out of nowhere.
I rarely use it now since moving away from that icy hellhole in the Midwest but I still keep it around. You never know, I might need it when I get old and infirm
Our cats really like the electric heated pillows to lay on. We keep the house ~60F so if we're out for a significant period of time, the hot water bottle wouldn't work. Plus good luck getting a kid to hold on to a hot water bottle while moving around.